Pin centering device and cushion retainer



NQV. 22, 1932. J. c. ROBERTSON PIN CENTERING DEVICE AND CUSHION RETAINER Filed March 12, I929 Patented Nov. 22, 1932 UNITED STATES PATENT OFFICE JOHN CULLEN ROBERTSON, or ANNAroLIs, MARYLAND, ASSIGNOR T0 Looxn INSUL TOB CORPORATION, or BALTIMORE, MARYLAND, A CORPORATION or MARYLAND PIN CENTERING DEVICE AND CUSHION RETAINER Application. filed March 12, 1929. Serial No. 346,406,

The invention relates to high tensioninsulators, particularly those of that type in which the dielectric body has a recess within which is secured a pin which, in the case of a suspension insulator, is provided for the purpose of making mechanical connection with another unit or with a conductor holder, or which, in the case of other types, constitutes a stationary support.

It is well known that it is a common practice to secure the pin within the recess by means of cement. It is readily apparent that the pin should be concentric with the recess so that the cement will be of uniform thickness at every cross sectional horizontal plane toiavoid trouble on account of the differences between the coefficients of expansion of the dielectric material, the cement and the metal of the pin. Furthermore, it has been discovered in actual practice that it is desirable to provide a pad or yieldable element at the end of the pin capable of being compressed upon shrinkage of the materials at low temperatures, a certain degree of relative axial movement of the parts occurring at such a time. In some instances the pin head has simply been coated with hot asphaltum or the like and in other instances it has been proposed to use a compressible disk, the exact nature of which is immaterial. In this latter mentioned case the problem has arisen of how to maintain such a disk in proper position without danger of slipping while the insulator is assembled and the cement applied.

It is with the above facts in view that I have devised the present invention which has for its general object the provision of means adapted for use in conjunction with an insulator pin for the purpose of positively centering the pin with respect to the recess or cavity within which it is to be secured.

An important object of the invention is to provide. a centering device of this character which will perform its function with accuracy notwithstanding the existence. of unavoidable manufacturing variations in the size of the pin hole or recess, the device being moreover capable of operating accurately in case of employment in connection with insulators having recesses of purposely different diameters.

Another important object of the inventionis to provide a centering device of this type which serves as means for retaining upon the pin a disk of compressible material serving as a cushion or pad.

A more specific object of the invention is to provide a device of this character which may be initially applied to the. pin and which may remain thereon and be incapable of accidental disconnection therefrom prior to assembly of the insulator, the advantage being that a plurality of the devices may be prepared for subsequent use.

An additional object of the invention is to provide a device of this character which will be very simple and inexpensive to manufacture, easy to apply, positive in action, efficient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and illustrated in the accompanying drawing in which:

Figure 1 is a vertical cross section through an insulator of the suspension type showing it assembled with my device in applied position,

. Figure 2 is a horizontal cross section taken on the line 2-'2 of Figure 1,

Figure 3 is a fragmentary side elevation of the pin with the device thereon, and

Figure 4 is a plan view of the device alone.

Referring more particularly to the drawing I have shown. an insulator of the suspen sion type including a dielectric body 1 having an upstanding neck portion 2 carrying a metal cap 3 and formed with a recess 4 for the reception of a pin 5 which is here di closed as having a head 6 of stepped formation. Usually the wall of the recess is roughened either by means of sanding or by forming it with projections 7. However, this is a detail of general practice and forms no part of the present invention though it should of course be understood that the purpose is to insure the proper holding action between the insulator body and the cement 8 which embeds the pin in the recess.

In the assembly of insulators of this and in fact any type in which a pin is secured within a recess, there is the problem of centering the pin with respect to the recess. In carrying out the present invention I provide a centering device adapted to be initially mounted upon the pin and having means engaging and cooperating with the recess wall for bringing and maintaining the pin in coaxial relation to the body or the recess therein. In the present instance this means is shown as comprising a disk 9 which may be readily and cheaply stamped out from sheet material, preferably a substantially non-corrodible metal of a more or less resilient nature, such forinstance as sheet copper, brass or the like. This disk is preferably of substantially the same diam eter as the pin head and is likewise preferably shaped to conform substantially to the end thereof, that is to say it is concavo-convex in cross section. If, however, the pin should be flat across the end the disk may likewise be flat though the first mentioned formation is the better. This disk is formed with a plurality of outstanding lugs 10 of any desired number and of such length that the distance between the center of the disk and the outer ends of three or more of the lugs will be equal to or possibly slightly greater than the radius of the inner portion of the recess 4 as certain of the lugs are intended to engage against the recess wall as shown in Figure 1. It is not necessary that all of the lugs be of the same length though it is convenient to make them so inasmuch as certain of the lugs need be only'long enough to be bent about the edge of the outermost step on the pin head so as to retain the disk in place upon the end of the If desired, use may be made of a compressible or yieldable disk 11 which is located between the end of the pin and the disk 9, this disk 11 constituting and being hereinafter referred to as a pad or cushion. The exact nature of this pad is of minor importance and it may easily be formed of thin sheet cork or some other analogous substance.

In the use of the device, the disk 9, either with or without the pad 11, is placed upon the end of the pin head 6 and preferably alternate ones of the lugs 10 are pressed or otherwise bent downwardly to'engage over the endmost step on the pin. These downwardly bent lugs are indicated in Figure 3 at 10". The remaining lugs are permitted to extend outwardly in their natural or substantially straight position as shown at 10 in the same figure. The downwardly bent lugs 10 operate to hold the device upon the pin so that there will be no displacement prior to or during assembly of the insulator. The pin thus equipped with the device is then inserted within the recess 4 manually or by any suitable pin placing machine and it is apparent that any means whatsoever may be employed for holding the outer or free end of the pin centered with respect to the insulator body. Upon insertion of the pin within the recess the outwardly extending lugs 10 engage against the recess wall and thus guide the pin to its proper position and hold it there. If the bottom of the recess should be of slightly less radius than the distance between the center of the disk and the outer ends of the lugs intended to engage against the recess wall, the resilient nature of the material from which the disk is formed will permit the lugs to give or yieldso that the centering will be effected nevertheless. The cement 8 is then poured in in the usual manner and will embed the pin and hold it permanently associated with the insulator body.

From the foregoing description and a study of the drawingitwill be apparent that I have thus provided an extremely inexpensive device by means of which pin centering may be effected with certainty and accuracy. By the employment of this means it will be seen that the thickness of the cement about thepin will be uniform so that no internal strains or stresses will be set up on account of the differences between the coefficients of expansion of the different materials, porcelain, cement and metal. The mechanical and electrical strength of the insulator is thus mad greater.

lVhile I have shown and described the preferred embodiment of the invention, it should be understood that the disclosure is merely illustrative as I reserve the right to make all such changes in the detailed formation as will not depart from the spirit of the invention'or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. The combination with an insulator hav ing a pin cemented within a recess thereof, of

means for centering the pin within the recess, sa1d means comprising a member embracmgly engaged upon the pin and having. out? wardly extending portions engaging against the recess wall, and a yieldable pad inter- 3. The combination with an insulatorhav- 7 ing a pin cemented within a recess thereof, of means for centering the pin within the recess,

said means comprising a member covering the end of the .pin and having outstanding pore tions bearing against the recess wall, and a yieldable pad interposed between said member and the end of the pin.

4. The combination with an insulator having a pin cemented Within a recess thereof, of means for centering the pin within the recess, said means comprising a member having portions retainingly engaged upon the pin and a plurality of outstanding portions with their ends abutting against the recess wall, and a pad within said member contacting the pin.

5. The combination with an insulator having a pin cemented within a recess thereof, of means for centering the pin within the recess, said means comprising a member covering the end of the pin and formed with a plurality of radial lugs having their enos engaging against the recess wall, and non-metallic means within said member engaging the pin.

6. The combination with an insulator havin g a pin cemented within a recess thereof, of means for centering the pin within the recess, said means comprising a member disposed upon the end of the pin and formed with a plurality of portions embracing the same and a plurality of other portions engaging against the wall of the recess.

7. The combination with an insulator having a pin cemented within a recess thereof, of means for centering the pin within the recess, said means comprising a member disposed upon the end of the pin and formed with a plurality of portions embracing the same and a plurality of other portions engaging against the wall of the recess, the first and second named portions being arranged in alternation.

8. The combin ation with an insulator having a pin cemented within a recess thereof, of means for centering the pin within the recess, said means comprising a member disposed upon the end of the pin and formed with a plurality of portions embracing the same and a plurality of other portions engaging against the wall of the recess, the first and second named portions being arranged in alternation, and a yieldable pad located within said member and confined between it and the end of the pin.

9. The combination with an insulator l1aving a pin cemented Within a recess thereof, of means for centering the pin within the recess, said means comprising a member cov ering the end of the pin and formed with a series of outstanding lugs certain of which embracingly engage the pin and certain of which. engage against the wall of the recess.

10. The combination with an insulator having a pin cemented within a recess thereof, of means for centering the pin within the recess, said means comprising a member disposed upon the end of the pin and formed with a plurality of outstanding lugs alternate ones of which embracingly engage the end portion of the pin and the other alternate ones 

